Paper and board machines conventionally use blow boxes within the single-wire region for supporting the web. Such apparatuses are described in FI laid-open publication 69332 and FI laid-open publication 65460.
Air to the blow boxes is generally taken as recycle air from inside the hood of a paper machine or similar equipment. The recycle air is contaminated by, e.g., dust whose landing into the blow box clogs the orifice slots of the blow box at least partially, thereby worsening the efficiency of the box. Impairment of the box function causes web instability such as flutter, whereby the frequency of web breaks and other malfunctions increases. Obviously, such problems result in decrease of production output and profitability at the paper machine or similar equipment.
It is an object of the present invention to achieve a method capable of overcoming the problems associated with the clogging of the blow boxes. A further object is to attain apparatus implementing said method, suited for rapid and easy cleaning of the orifice slots.